Keratin polypeptide hydrolyzates as hair treating agents

ABSTRACT

The invention relates to compositions for the treatment of filamentous keratins, for example, to cosmetic compositions for the treatment of human hair and compositions for modifying animal hair or fur. The compositions are made up of water soluble peptide products of partial hydrolysis of keratinaceous materials, such as hog hair, resulting from hydrolysis using acids under conditions which, while breaking down the complex proteins, will leave a substantial portion of the disulfide linkages present in the keratinaceous materials intact. Filamentous keratins have the peptide products chemically bonded thereto by a two step process wherein disulfide linkages of both the peptide products and the filamentous keratins are split by the action of a reducing agent and disulfide linkages are then reformed by action of an oxidizing agent whereby at least some of the sulfhydryl groups of the peptide products formed by the action of the reducing agent are bonded to sulfhydryl groups of the filamentous keratins.

i 51 Oct. 22, 1974 KERATIN POLYPEPTIDE HYDROLYZATES AS HAIR TREATINGAGENTS [75] Inventor: Sulo A. Karjala, Chicago, Ill.

[73] Assignee: Wilson-Sinclair C0., Oklahoma City,

Okla.

22 Filed: May 27,1971

21 Appl. No.: 147,622

[52] U.S. Cl 1. 132/7, 8/127.5l, 424/71, 424/72 [5]] Int. Cl A61k 7/10[58] Field of Search 424/71, 72; 132/7; 8/1275], 128

I [56] v References Cited UNITED STATES PATENTS 2,540,494 2/1951 Schwarz424/72 3,628,974 12/1971 Battista 424/70 FOREIGN PATENTS OR APPLICATIONS1,434,991 3/1966 France 424/71 OTHER PUBLICATIONS Burnett, Am. Per. &Cos., Vol. 78, No. 10 (1963) pp. 69-72.

Primary Examiner-Vincent D. Turner Attorney, Agent, or FirmDressler,Goldsmith, Clement & Gordon, Ltd.

[ 5 7] ABSTRACT The invention relates to compositions for the treatmentof filamentous keratins, for example, to cosmetic compositions for thetreatment of human hair and compositions for modifying animal hair orfur. The compositions are made up of water soluble peptide products ofpartial hydrolysis of keratinaceous materials, such as hog hair,resulting from hydrolysis using acids under conditions which, whilebreaking down the complex proteins, will leave a substantial portion ofthe disulfide linkages present in the keratinaceous materials intact.Filamentous keratins have the peptide products chemically bonded theretoby a two step process wherein disulfide linkages of both the peptideproducts and the filamentous keratins are split by the action of areducing agent and disulfide linkages are then reformed by action of anoxidizing agent whereby at least some of the sulfhydryl groups of thepeptide products formed by the action of the reducing agent are bondedto sulfhydryl groups of the filamentous keratins.

2 Claims, No Drawings l KERATTN POLYPEPTIDE HYDROLYZATES AS HAIRTREATING AGENTS This invention relates to materials for modification offilamentous keratins such as human hair, animal hair and similarfilamentous keratin products by being chemically bonded thereto so as tobecome an integral portion thereof. More particularly, it relates. to amethod for the coupling of the product of partial hydrolysis of akeratinaceous material to filamentous keratins by cross-linking ofsulfiiydryl groups to improve such characteristics as strength andmanageability and to impart gloss.

ln accordance with this invention, compositions derived from naturalsources of keratin by hydrolysis under conditions to preserve asubstantial portion of the disulfide linkages of the peptide or aminoacid such as cystine intact, are produced which have utility in aqueousmedia for treatment and protection, during treatment of filamentous typekeratin materials, such as human hair, animal hair such as wool, fur,etc.

Hair, including human hair, and the animal hairs such as wool and fur,consists of strands .of keratin fibers surmounted by a scaly cuticle ofkeratin protein. Keratin is unique in its content of sulfur-containingamino acids, in particular the amino acid cystine. The disulfidelinkages of cystine can be broken. to produce at least one freesulfhydryl group by means of reducing agents, and the linkages can bereclosed to recover the original cystine by use of an oxidizing agent.If hair strands are placed under stress, many of the cystine disulfideunits are ina state of tension. If the strands are treated with areducing agent while under stress, the disulfide units are broken. If,while still under stress, after the disulfide units have been opened up,the strands are subjected to an oxidizing agent, the disulfide units arereformed, but now they are reformed with different half-cystine units ina way that the stress now leaves the strands in their new position,since the geometry of the strands is locked in to the new configuration.This is the basis of the well-known permanent wave process in which thehair is treated after curling with ammonium thioglycolate to open up thedisulfide bonds, after which the curled hair is oxidized with sodiumbromate or other oxidizing agents to form the permanent curl.

It is well known that proteinaceous materials can be produced of acharacter which can be adsorbed or absorbed or both when applied tohair. The disadvantage of the hydrolyzed proteins such as gelatin, etc.,is the non-uniformity in hydrolysis, the salt content present due toneutralizing the hydrolyzingagents, and the loss of significant amountsof the hydrolyzates when the treated hair is subjected to rinses, etc.

It is also well known that treatment of filamentous keratin materialssuch as human hair with reducing agents will effect cleavage of thedisulfide linkages. Where the hair, wool, etc., are treated withreducing and oxidizing agents such as when treating with hairwavingpreparations, the action is damaging and results in a marked loss inweight from virgin hair strands, and the hair becomes weak and brittle.Such damage is accentuated when such treatments are applied to bleachedhair.

in keratin fiber dyeing procedures, such as those used in the treatmentof wool, it is generally necessary to heat the keratin fiber with thedye in water at the boiling point to insure fastness of the dye. Theresults of such treatment are that with a fast dye the color can nolonger be removed readily and the keratin fibers become tenderized bythe treatments to add or remove the dye.

Reducing and oxidizing agents are commonly used in the creating ofpermanent wave sets for human hair. The hair is put under stress as bywinding on rollers and a reducing agent applied, such as ammoniumthioglycolate, after which the reagent is drained off or rinsed out andthe hair treated with an oxidizing agent such as sodium bromate orhydrogen peroxide. During treatment with the reducing agent, the stresson the hair is minimized by the opening up of the cystine disulfidelinkages. Upon oxidation, cystine disulfide linkages are reformed butthe closure occurs between not only a portion of the original sulfhydrylgroups which developed during the reduction splitting but primarilybetween sulfhydryl groups which have been brought into close proximityas a result of distortion of the keratin filaments due to the appliedstress. By such action, the hair strand is reformed but with a new wavedstructure. This remains as a permanent feature of the hair-strands untilthe hair is subjected to another waving procedure or until the hairstrands grow out.

Now it has been discovered that if keratin-containing material, such ashog hair, is partially hydrolyzed through the use of dilute phosphoricacid or of multifunctional organic acids in a manner such that asubstantial proportion of the cystine disulfide units are retainedintact, the keratin polypeptides obtained have interesting properties.

Since the chemical composition of the keratin polypeptide hasconsiderable similarity to that of the hair or wool, there is no directchemical proof that a reaction occurs to link the polypeptide directlyto the hair other than by the use of keratin polypeptides containingradioactive elements. However, after treatment of the hair or wool withthe reducing agent containing the keratin polypeptide, there isgenerally a gain in weight of the hair or wool swatch, while with thereducing agent alone there is a sharp loss in weight. The hair alsoretains its structure, form and sheen in the presence of thepolypeptide, while keratins treated with the reducing agent alone showbrittleness, shrinkage and loss in strength.

A more definitive proof that linkage has occurred is demonstrated whenthe keratin polypeptides are coupled through their free amino groups toa diazotized dye intermediate by known means, and the dye coupledkeratin polypeptide is isolated. When human hair or wool is treated inpH 9.2 buffer with the dyecoupled polypeptide and washed with water, allof the dye-coupled polypeptide washes out, since there has been nochemical combination of the two components and there is little or nophysical sorption of the dyecoupled derivative upon the hair or wool.If, however, the dye-coupled polypeptide is dissolved in ammoniumthioglycolate at pH 9.2, and the human hair or wool is treated with thissolution, drained and reoxidized with a mild oxidant, the hair strandsor wool swatches are permanently dyed, and the dye cannot be washed outwith water, detergents, acids or alkalis, or organic solvents.

Coupling of the dye-keratin polypeptide derivative with the hair or wooloccurs at room temperature, and there is no necessity for heating thereaction mixture in boiling water. The extent of linkage of thedye-keratin polypeptide complex to the hair or wool is a function of theconcentration of the complex in the reducing solution, the concentrationof added unmodified keratin polypeptides, if any, and the reaction timeused. Thus, by modifying the conditions, any shade or tint of the dyecan be obtained.

Wool can be modified in the form of yarn, or after weaving. Permanentprints can be made on wool if, for example, dry virgin wool is treatedwith solutions of the keratin-dye complex in a reducing solution bymeans of a printing roller in which the design is transferred to theflannel, dried andsubjected to a flow of air to obtain atmosphericoxidation, or passed through a dilute solution of mild oxidant, washed,and dried by normal means.

As has been pointed out above, the modification impressed on the hair orwool is permanent and is not removed by the ordinary rinse or shampootreatments. There is one method, however, by which the modified keratinpolypeptide can be substantially removed from the hair or wool product.This method is to treat the hair or wool product with thioglycolatealone, in order to reopen the disulfide linkages, wash the product wellwith water, and reoxidize with a mild oxidant. However, since repeatedreductant and oxidant treatments tend to degrade the hair or wool, it ispreferred to inhibit the degradation by adding unmodified keratinpolypeptide to the reductant, so the modified derivative is replacedsubstantially by unmodified keratin polypeptide which has the ability tominimize the damage to hair of such chemical actions.

When preparing the keratin polypeptide having utility as hair modifiers,the number of intact disulfide linkages remaining in the keratinpolypeptides is dependent upon the purity and cleanliness of the initialhog hair, and the processing conditions for hydrolysis. The cleaner thehair, the higher is the amount of intact disulfide linkage. The moredrastic the digestion conditions generally the lower the amount ofintact disulfide linkages. Since, in a partial hydrolysis, the productwill be made up of a heterogeneous mixture of substances of differentmolecular weights, the measure of disulfide units is an average one. Onseparation of a hydrolysis mixture by reverse osmosis, it was found thatthe lowest molecular weight fraction, below 1,000, had the smallestnumber of intact disulfide linkages, while the fraction of molecularweight 1,000 to 10,000 had a larger number, and the fraction with amolecular weight over 10,000 had the largest number of intact disulfidelinkages. 1

The extent of disulfide units is measured by known means, using apolarograph and a rotating platinum electrode, with titration of thesulfhydryl groups amperometrically with methyl mercuric iodide. Underoptimum conditions, hydrolysis of clean hog hair with 85 percentphosphoric acid for to minutes at 135C. gives a product which showsapproximately 50 moles of disulfide linkage per 100,000 grams of hair.This value approximates the value for the total sulfur content of thehair. Under plant operating conditions, however, where it isuneconomical to purify the hair completely and the use of highlypurified reagents is impractical, intact disulfide values of 15 to 49moles per 100,000 grams are normally found, which is the product ofsubjection of keratin-containing material to heat for period of 1 to 24hours at temperatures in the range between 100C. and 160C. in thepresence of acid having a concentration in the range between 4 andpercent and in quantities to maintain a pH of less than 4 throughout thehydrolysis reaction, said period varying inversely with the temperaturelevel. All keratin polypeptides, for example, dipeptides, tripeptides,tetrapeptides, etc. provided the peptides still contain one or moreintact cystine units, are applicable for use in this invention.

In Table I are listed a few of the results obtained by the use of thisinvention. These results are based on weight changes, so relativedifferences in one series are comparable. However, it is not alwayspossible to compare the results in one series with those in another,since the weight changes are occasionally modified by changes inmoisture content due to changes in relative humidity.

.After treatment with keratin polypeptide, the samples were washedthoroughly with water and detergent, dehydrated with acetone, andfinally air-dried.

After treatment with ammonium thioglycolate the samples were washed withwater, oxidized for 5 minutes with 1.5 percent sodium bromate solution,washed again with water and detergent, dehydrated with acetone, followedby air-drying.

After treatment with mixtures of keratin polypeptides and ammoniumthioglycolate, the samples were drained a short time to remove theexcess solution, after which they were oxidized with 1.5 percent sodiumbromate solution for 5 minutes, and washed and dried as above.

The wool swatches were percent worsted flannel, and the human hairsamples were of white virgin hair and a medium bleached hair obtainedfrom commercial sources. I

The invention will be further understood from the following exampleswhich are given for the purposes of illustration and without anyintention that the invention be limited thereto.

The method of preparing a water soluble product by partial hydrolysis ofkeratinaceous materials is as follows:

EXAMPLE 1 To 100 grams of 75% H PO heated in a large test tube to C. toC. in an oil bath, was added portions of hair over a period of 5 hours.A total of 56 grams of hair was added, and this amount appeared to beabout the maximum which could be added under these conditions. Themixture was heated for another 1.5 hours at this temperature, andcooled. No un changed hair particles were observed. The mixture was thendiluted with 4 to 5 volumes of water, centrifuged to remove darkinsoluble material, and the supernatant, at pH 1.7, was brought up to pH6.7 with solid CaCO The light yellow filtrate was concentrated toapproximately 50 percent polypeptide solids by vacuum evaporation.

The method of treating hair to incorporate the products of hydrolysis asan integral part of filamentous keratins is illustrated by the followingexamples.

EXAMPLE I1 50 grams of the dry hydrolyzate product of Example 1 weredissolved in 1,000 grams of aqueous solution containing 6 percent byweight of ammonium thioglycolate to form a 5 percent by weight solution.Coils of medium bleached hair strands were placed in the solution for 15minutes, the solution drained off and then the coils are oxidized bytreatment for 5 minutes with an aqueous solution containing 1.5 percentby weight of sodium bromate. The hair coils were then washed bromate.The wool segment was then washed with water, detergent, acetone, alcoholand finally ether.

Additional segments of wool flannel were similarly treated with 8percent ammonium thioglycolate soluwith water, detergent, acetone,alcohol and finally 5 ti0n not Containing y hydrolyzala ether.Additional coils of the medium bleached hair Additional Segments of woolflannel were treated in were similarly treated with the 6 percentammonium a Similar manner Whh an 8 Pemeht thioglycolate 50h!thioglycolate solution not containing any hydrolyzate. lion containing10 P and 20 Percent by Weight of Similar coupling operations werecarried out on white the hydrolyzate P d of Example virgin hair using 6percent ammonium thioglycolate so- 10 Details of the additional wooltreatment and the mu sults thereof are set forth in Examples VI and VII.

- EXAMPLE V EXAMPLE 200 grams of the dry hydrolyzate product of Example250 grams of the dry hydrolyzate P od O Ex pl I were dissolved in 1,000grams of aqueous solution I were dissolved in 1,000 grams of aqueoussolution tai i 4 percent by weight of ammonium thioglycontaining 6percent by e ght of am on t gly-- colate solution to form a percent byweight solution. colate to form a percent by weight solution. Coils ofSegments of wool flannel were placed in the solution medium bleachedhair strands were placed in the soluf r on half hour, the solutiondrained off and then oxition for 15 t the Solution drained off and th 20dized by treatment for 5 minutes with an aqueous soluoxidized bytreatment for 5 minutes with'an aqueous tion containing 1.5 percent byweight of sodium brosolution containing 1.5 percent by weight of sodiummate. The wool segment was then washed with water, bromate. The haircoils were then washed withwater, detergent, acetone, alcohol andfinally ether. detergent, acetone, alcohol andv finally ether. Addi- Theweight changes effected by the treatments detional coils of the mediumbleached hair were similarly 25 scribed in Examples 11 through V are setforth hereinaftreated with the 4 percent ammonium thioglycolate solutionnot containing any hydrolyzate. Similar coupling operations were carriedout on white virgin hair using 4 percent ammonium thioglycolatesolutions.

ter in Table 1. Table 1 also shows the result of subsequently treatingthe products with thioglycolate solutions with and without the presenceof the polypeptide product of Example 1.

TABLE 1 Initial Treatment Subsequent Treatment Keratin Keratin Sampleand Polypep- Thio- Weight Po1ypep- Thio- Weight Reaction Time tideglycolate Change tide glycolate Change Wool Flannel 20% 0% +0.02% 56hour 20% 4% +0.8

20% 4% +0.65% 0 4% -2.6% Medium Bleached 25% 4% +2.4 Hair 25% 4% +3.6 04% 9.3% b hour 0 4% 1 1.0% Medium Bleached 5% 0 l.0 Hair 0 6% -8.5 15minutes 0 6% -l0.0% 5% 6% +0.97% 5% 6% 6.1 0 6% 3.0 5% 6% -6.1 WhiteVirgin 5% 0 +0.31% Hair 0 6% 0.9% 1 hour 0 6% '-0.54% 5% 6% EXAMPLE IVEXAMPLE V1 grams of the dry hydrolyzate product of Example 1 weredissolved in 1,000 grams of aqueous solution containing 8 percent byweight of ammonium thioglycolate to form a 5 percent by weight solution.Segments of wool flannel were placed in the solution for one half hour,the solution drained off and the wool flannel then oxidized by treatmentfor 5 minutes with an aqueous solution containing 1.5. percent by weightof sodium Three swatches of 100 percent worsted wool test flannel weretreated as follows:

99.52 mg 88.82 mg 1 hr. 1 hr.

10% solution 10% solution 10% solution Sample 1 was washed 4 times withwater, while samples 2 and 3 were drained f6i55'ir6r't time oxidizedwith 1.5 percent sodium bromatefahd washed four times in water, afterwhich all sarfifliwre ain dried overnight. 7

Weight of Sample 98.87 mg 90.58 mg 9226 mg Weight change 0.65 mg +2.72mg +3.44 mg X Weight change .6S% +3.1'7o +3. 3%

Sample 2 was immersed for one hour in 8 percent ammonium thioglycolate,washed well with water, oxidized with 1.5 percent sodium bromatesolution, washtide under these conditions essentially balances out thenormal weight loss to be expected from thioglycolate treatment. Anincrease in color occurs from Sample 5 to 7 since the peptide is darkerthan the flannel swatch.

ed again with water, and air dried.

to The effect of the keratin peptides on samples of medium bleachedhuman hair is shown in the following example. In this case, all of theoriginal samples showed Final weight of sample 86.98 mg weight losses asa result of humidity changes on standwelsh ham? mg ing overnight.However, the relative weight changes are Change 4.l4%

15 of greater importance than the absolute changes.

"EXAMPLE VIII Sample No. 8 9 10 11 12 Weight sample 19.28 mg. 37.52 mg.41.24 mg. 30.12 mg. 87.84 mg. Treatment time 15 min. 15 min. 15 min. 15min. 15 min. Keratin peptide in pH 9.2 buffer 5% sol. 0 0 5% sol. 5%sol. Ammonium thioglycolate pH 9.2 0 6% 6% 6% 6% Treatment of human hairor wool with ammonium thioglycolate always results in a loss in weightof the ples 9, 10, 11 and 12 were immersed in 1.5 percent sosample, butin the presence of keratin polypeptides dium bromate for 5 minutes,washed well with water, there is a gain in weight, or, at the most, asmaller loss and air dried.

Sample 8 w a s washed in water an d dried, while sam- Weight after 19.08mg. 34.32 mg. 37.12 mg. 28.28 mg. 73.12 mg. drying Weight change -0.20mg. 3.20 mg. 4.l2 mg. l.84 mg. -4.72 mg. Weight change 1.0% 8.5% 10%6.l% 6.1%

in weight than when ammonium thioglycolate is used alone without keratinpeptides. This is shown in Sample 3 which showed a sharp loss in weightwhen treated with the reducing agent alone. The insignificant change inweight in Sample 1, treated with the keratin polypeptides alone at pH9.2, shows that the increase in weight is not due to sorption of thepolypeptide.

There is thus less weight loss in the presence of keratin peptide. Thehair samples 11 and 12 were smooth, soft and silky, very similar to theinitial samples and 40 Sample 1.

Samples 10 and 11 were treated as follows:

Sample 10 Sample 11 EXAMPL V E n Treatment time 15 minutes 15 minutesThe effect of increasing concentration of keratin Kemm P p In pH 9.2buffer 5% solution 0 polypeptides was shown when four swatches of thetest Ammonium mo 1 come W flannel were treated as follows: P 91 5% 3%Sample No. i i 4 5 i 6 7 Weight of sample 100.32 mg 101.52 mg 98.56 mg94.12 mg Treatment time 16 hr. 15 hr. '15 hr. 16 hr. 70 Keratinpolypeptide in pH 0.2 buffer 20% 5% 10% 20% Ammonium thioglycolate pHSample 4 was drained, washed well with water, and air dried. Samples 5,6 and 7 were drained, treated for 5 minutes with 1.5 percent sodiumbromate, washed Sample 10 was subjected to the same treatment as theinitial treatment of samples 1 l and 12, while sample 1 1 was given thesame treatment as that of samples 10 with water and air dried. and 11.

Weight of Sample 100.44 mg. 101.44 mg. 96.16 mg. 95.68 mg. Weight change+0.16 mg. +0.03 mg. +0.60 mg. +1.5 mg.

% Change +0.16% 0.079% +0.61% +1.65%

The samples were then allowed to dry.

Thus, this example again illustrates the protective action of keratinpolypeptide during treatment of human hair with reducing and oxidizingagents.

Since the weight changes which occur in the above examples are small,and at times may be overshadowed by weight changes due to changes inrelative humidity, a more positive demonstration is necessary to showthat the effect observed is actually due to a chemical reaction, withthe formation of stable covalent bonds which are much stronger than thebonds associated normally with sorption of peptides or protein by hairstrands. One indication is that shown in Example VII, in which the colorof the flannel swatches increases with increase in peptideconcentration. 7

Additional proof of the bonding of disulfide linkage containingpolypeptides to filamentous ke'ratins is shown by the following example.

EXAMPLE IX Cystine was converted to dinitrophenylcystine by a knownreaction with fluorodinitrobenzene. The product was crystallized fromalcohol, dissolved in ammonium thioglycolate, and swatches of woolflannel and coils of hair were immersed in the'solution for a shorttime, drained, and the keratin samples oxidized with dilutesodiumbromate, washed with water, detergent, and organic solvents. The brightgolden color in the samples was impervious to all solvents which did notdestroy the wool or hair swatches.

Similar results were obtained when keratin polypeptides, prepared asdescribed in Example I, were converted to dinitrophenyl derivatives bythe same reaction procedure.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention as set forth in theappended claims.

I claim:

1. A method of treating hair fibers to provide a permanently bondedprotective and conditioning content of disulfide-containingproteinaceous agent comprising contacting the hair with an effectiveamount of an aqueous composition containing water having dissolvedtherein from 4 percent to 8 percent by weight of ammonium thioglycolatereducing agent and from 5 percent to percent by weight of a watersoluble keratin polypeptide hydrolyzate having an intact disulfide unitcontent in the range between 15 and 49 moles of disulfide linkages per100,000 grams of hair, said hydrolyzate being produced by hydrolyzingkeratincontaining hair at l00l60C. in the presence of phosphoric acidhaving a concentration of 4 percent to percent until the disulfidecontent is in the range specified while maintaining a pH less than 4throughout the hydrolysis-reaction, draining off said aqueouscomposition, and then contacting said hair with an effective amount ofan aqueous solution of an oxidizing agent. 2. The method as recited inclaim 1 in which said oxidizing agent is selected from the groupconsisting of so- .dium bromate and hydrogen peroxide.

age UNITED YS'IA'IES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.8 I Dated October 22, 1974 Tqvefitoz-(%) v Sulo A. Karjala It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

' Column 3, line 10, after "wool" insert flannel. I

Column 7, in the first column of the first Table under Example VII,before "buffer'" ,"0. 2" should be 9.2,--.

Signed and sealed this 4th day of February 1975.

(SEAL) Attests MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting OfficerCommissioner of Patents

1. A METHOD OF TREATING HAIR FIBERS TO PROVIDE A PERMANENTLY BONDEDPROTECTIVE AND CONDITIONING CONTENT OF DISULFIDECONTAINING PROTEINACEOUSAGENT COMPRISING CONTACTING THE HAIR WITH AN EFFECTIVE AMOUNT OF ANAQUEOUS COMPOSITION CONTAINING WATER HAVING DISSOLVED THEREIN FROM 4PERCENT TO 8 PERCENT BY WEIGHT OF AMMONIUM THIOGLYCOLATE REDUCING AGENTAND FROM 5 PERCENT TO 25 PERCENT BY WEIGHT A WATER SOLUBLE KERATINPOLYPEPTIDE HYDROLYZATE HAVING AN INTACT DISULFIDE UNIT CONTENT I THERANGE BETWEEN 15 AND 49 MOLES OF DISULFIDE LINKAGES PER 100,000 GRAMS OFHAIR, SAID HYDROLYZATE BEING PRODUCED BY HYDROLYZING KERATIN-CONTAININGHAIR AT 100*-160=C. IN THE PRESENCE OF PHOSPHORIC ACID HAVING ACONCENTRATION OF 4 PERCENT TO 85 PERCENT UNTIL THE DISULFIDE CONTENT ISIN THE RANGE SPECIFIED WHILE MAINTAINING A PH LESS THAN 4 THROUGHOUT THEHYDROLYSIS REACTION, DRAINING OFF SAID AQUEOUS COMPOSITION, AND THENCONTACTING SAID HAIR WITH AN EFFECTIVE AMOUNT OF AN AQUEOUS SOLUTION OFOXIDIZING AGENT.
 2. The method as recited in claim 1 in which saidoxidizing agent is selected from the group consisting of sodium bromateand hydrogen peroxide.